(a) Field of the Invention
The present invention relates to a multiple saw blade adjustable dado cutter assembly. The cutter can be used with a table saw or a radial arm saw, for example, to make dado cuts in board lumber. A pair of cooperating cams, each connected to a saw blade, can be adjusted to make a dado cut of a desired width. If the desired dado width is wider than the two blade configuration can cut, a center cam attached to another blade can be inserted between the pair of cooperating cams. With the three blade configuration, the three cams cooperate to allow the three blades to be spaced for the desired width of cut. In both configurations and at any spacing width, the two or three blades employed remain in a generally parallel alignment and transverse to the axis of the arbor on which the assembly is secured. To permit the blades to function with this geometrical relationship and to be adjustable, not all of the blade teeth lie in the same plane. The sequentially operating three or more cam assembly has uses beyond dado cutting. Also, the blades can be made to mount directly onto a saw arbor with spacer washers taking the place of the cam assembly. For industrial applications, more than three blade configurations are envisioned.
(b) Description of the Prior Art
A dado, or housed joint, is typically made by cutting a slot into a board, the slot having a depth of cut equal to one half the thickness of the board, the slot being at a location other than the board end, and the slot having a width equal to the thickness of the other board which is to be fitted into the slot. Multiple blade dado cutters which can be adjusted to make cuts of differing width are known in the art. However, they have significant disadvantages when compared to the cutter of the instant invention.
The typical dado cutter for use in the home usually has blades which are adjusted so that a blade rotates in a plane which is not transverse to the axis of the arbor on which the blade is mounted. Basically, with this arrangement, the blade wobbles causing vibration forces and only one saw tooth cuts the outer side edge. For example, this alignment generally requires that the board being cut be fed through the cutter slowly and can cause the dado cut to have rough side edges and an uneven bottom cut. U.S. Pat. No. 4,589,458 teaches a two-bladed adjustable dado cutter employing a cam arrangement which permits the two blades to be adjusted for width of cut. The cam arrangement always keeps the two blades juxtaposed at one location along the blade circumference, with the widest spacing between the blades being at another location diametrically opposed from the juxtaposed location. The blades therefore form a V-shape which permits the wobbling forces to neutralize each other. This particular dado cutter is sold by Sears under the trademark "EXCALIBUR".
Various industrial dado cutters are known in which the blades rotate in planes which are transverse to the axis of the arbor on which the blades are mounted. However, with this configuration, to increase the width of cut, the basic outside two blades must be separated and additional chipper blades and paper shims must be inserted between them. For example, seven different blades may be involved with one dado cutter, the two outside blades which can each cut a width of 1/8 inch or 3.175 mm, four chipper blades which can each cut a width of 1/8 inch or 3.175 mm, and one chipper blade which can cut a width of 1/16 inch or 1.587 mm. By various combinations, this assembly can make dado cuts of from 1/4 inch or 6.350 mm to 13/16 inch or 20.637 mm in 1/16 inch or 1.587 mm increments. It should be appreciated that it is expensive to manufacture seven different blades which must function together in a plurality of arrangements.